JP2011037070A - Ejection control mechanism and ejection control method of printer - Google Patents

Abstract

Reflecting the measured moving speed of the conveying belt and the speed fluctuation of the recording medium between the recording medium conveying means, the ink ejection at the time of printing is accurately controlled and landing deviation is prevented.
A belt including a driven roller encoder 312 that measures a moving speed of a conveying belt 160 and a moving speed of a recording medium, a feeding-side encoder 313, and a discharging-side encoder 314 are measured. A speed difference data calculation unit 331 that calculates data corresponding to image positional deviation based on the difference between each speed from the moving speed, the paper feeding side speed, and the paper discharging side speed, and a memory for storing the speed difference data Section 333, correction control section 332 that corrects the detection signal input from driven roller encoder 312 with reference to the speed difference data, and positional deviation between the plurality of images on the conveyor belt based on the corrected detection signal Is provided with an ejection control unit 334 that controls the timing of ink ejection by the ink head.
[Selection] Figure 2

Description

  The present invention relates to a discharge control mechanism and a discharge control method of a printing apparatus that forms an image by discharging ink from the ink head onto the surface of a recording medium that is transported on a transport belt in a transport path.

  2. Description of the Related Art Conventionally, there is an ink jet system as one of printing apparatuses that form an image on a recording medium. In this method, recording paper is transported using an endless transport belt, and a plurality of ink heads arranged in the transport direction are sequentially passed to superimpose single-color images on a recording medium. An image can be obtained.

  By the way, in the printing apparatus using the above-described conveyance belt, there is a problem that the moving speed of the belt changes due to thickness unevenness in the belt circumferential direction. More specifically, this thickness unevenness is caused by, for example, uneven thickness in the belt circumferential direction. When such belt thickness unevenness exists, a thick belt portion is wound on the driving roller that drives the belt. When the belt is moving, the belt moving speed is increased. On the other hand, when a portion with a thin belt is wound, the belt moving speed is decreased, and the belt moving speed varies.

  Thus, if the moving speed of the conveying belt (conveying speed) is not maintained at a constant speed, each monochrome image is transferred when a plurality of ink heads form each monochrome image on a recording medium and these colors are superimposed. A so-called “landing deviation” occurs in which the positions are relatively shifted. When such landing deviation occurs, for example, a fine line image formed by overlapping images of a plurality of colors appears blurred, or white spots occur around the outline of the character image in the background image.

  In order to prevent such landing deviation, for example, there is a technique disclosed in Patent Document 1. In the technique disclosed in Patent Document 1, a roller encoder for detecting the moving speed of the conveying belt is attached, the moving speed of the conveying belt is detected, and each ink is detected based on the fluctuation of the moving speed due to the uneven thickness of the conveying belt. The ink ejection timing in the head is corrected to prevent landing deviation on the recording medium.

Japanese Patent No. 2820433

  In image formation of a printing apparatus using a conveyance belt, a plurality of recording media are supplied from upstream to downstream of the conveyance path until the recording medium is supplied onto the conveyance belt and sent out from the conveyance belt after image formation. Are sequentially delivered and conveyed by the driving means. For this reason, the moving speed of the recording medium on the conveying belt varies depending on the driving speed of each upstream and downstream driving means.

  However, just by adjusting the discharge timing based on the fluctuation of the moving speed due to the uneven thickness of the belt as in the invention disclosed in Patent Document 1, the speed difference between the upstream drive means and the downstream drive means is caused. There may be a difference in speed between the moving speed of the conveying belt and the moving speed of the recording medium on the conveying belt. In particular, when the printing processing speed is increased, the influence of the speed difference is increased, and there is a possibility that landing deviation that cannot be adjusted by adjusting the ejection timing may occur.

  Accordingly, the present invention has been made in view of the above problems, and in a printing apparatus including a transport mechanism that transports a recording medium by a transport belt, the speed between the transport speed of the transport belt and the travel speed of the recording medium. It is an object of the present invention to provide a printing apparatus and an ejection control method thereof that can reflect the difference, accurately control ink ejection during printing, and prevent landing deviation.

  In order to solve the above-described problems, the present invention provides a discharge control mechanism for a printing apparatus that forms an image by discharging ink from an ink head onto the surface of a recording medium transported on a transport belt in a transport path. A belt moving speed that is a moving speed of the belt, a feeding side speed that is a moving speed of the recording medium entering the conveying belt upstream of the conveying belt, and a moving speed of the recording medium that is sent from the conveying belt downstream of the conveying belt. The speed difference data calculation unit that calculates the data corresponding to the positional deviation of the image based on the difference between the respective speeds of the discharge side speed as speed difference data, and the speed difference data calculation unit during the printing process. Based on the measured speed difference data, the timing of ink ejection by the ink head is controlled so that the positional deviation between the plurality of images on the conveyor belt is reduced. And a discharge control unit for.

Another invention is a discharge control method for a printing apparatus, in which an image forming unit forms an image on a recording medium transported on a transport path.
(1) The belt moving speed that is the moving speed of the conveying belt, the paper feeding side speed that is the moving speed of the recording medium entering the conveying belt upstream of the conveying belt, and the recording medium sent from the conveying belt downstream of the conveying belt. A speed difference data calculating step for calculating data corresponding to the positional deviation of the image based on the difference between the respective speeds of the paper discharge side speed, which is the moving speed, as speed difference data;
(2) During the printing process, based on the speed difference data calculated by the speed difference data calculation unit, the timing of ink ejection by the ink head is controlled so that the positional deviation between the plurality of images on the conveyor belt is reduced. A discharge control step.

  According to these inventions, the image is based on the difference between the belt moving speed, which is the moving speed of the conveying belt, the paper feeding side speed, which is the moving speed of the recording medium upstream and downstream, and the discharging side speed. Data corresponding to the positional deviation is used as speed difference data. That is, in the present invention, during printing processing, it occurs according to changes in the degree of influence (for example, the contact area of the recording medium with respect to the conveyance belt and the frictional force due to the area) acting on the recording medium due to the speed difference of the belt moving speed. The positional deviation of the image is used as the speed difference data, and the printing timing is changed so that the positional deviation of the image does not occur, so that the landing deviation can be eliminated.

  In the above invention, the storage unit for storing the speed difference data calculated by the speed difference data calculation unit and the speed difference data stored in the storage unit based on the belt moving speed during the printing process are referred to from the belt speed measuring unit. A correction control unit for correcting the input detection signal, and the storage unit stores the speed difference data in correspondence with the magnitude relationship between the paper feeding side speed and the belt moving speed, and the paper discharging side speed and the belt moving speed. The correction control unit preferably refers to the speed difference data based on the magnitude relationship.

  In this case, the positional deviation of the image based on the difference between the moving speed of the conveying belt and the moving speed of the recording medium is stored as speed difference data, and the belt moving speed is measured during actual printing processing. By reflecting the speed difference data in the result, it is possible to change the printing timing so as not to cause the printing position deviation, and to eliminate the landing deviation. Furthermore, according to the present invention, the magnitude relationship between the paper feeding side speed and the belt moving speed and the paper discharging side speed and the belt moving speed can be reflected as the speed difference data, and the ink ejection timing can be controlled more appropriately. Can be done.

  In the above invention, the transport path includes an upstream path for supplying a recording medium to the transport belt on the upstream side of the transport belt, and the upstream path is located upstream of the transport belt by collecting a plurality of paper feed paths. The speed difference data is calculated for each of the plurality of paper feed paths, and the calculated speed difference data is stored in the storage unit in association with each corresponding paper feed path, and the correction control unit Preferably, the detection signal input from the belt speed measuring unit is corrected with reference to speed difference data corresponding to the paper feed path through which the recording medium for printing is fed.

  In this case, since the ink ejection timing control is changed in accordance with the conveyance conditions unique to each path in the paper feed path configured by a plurality of paths, the landing deviation can be more appropriately eliminated. it can. Here, the transport conditions include the length of the paper feed path and the paper discharge path, the number of bends, or the number of rollers, and further include acceleration / deceleration of the registration rollers during transport.

  In the above invention, the conveyance path includes a downstream path for sending the recording medium from the conveyance belt on the downstream side of the conveyance belt. In the downstream path, a plurality of discharge paths are branched from the conveyance belt, and the speed difference is determined. The data is calculated for each of a plurality of paper discharge paths, and the calculated speed difference data is stored in the storage unit in association with each corresponding paper discharge path, and the correction control unit has a recording medium for printing. It is preferable to correct the detection signal input from the belt speed measuring means with reference to the speed difference data corresponding to the discharged paper discharge path.

  In this case, in the paper discharge path where a plurality of paths are branched, the ink ejection timing control is changed according to the conveyance conditions unique to each path, so that landing deviation can be eliminated more appropriately.

  In the above-mentioned invention, it further comprises a paper type acquisition means for acquiring the size, type or thickness of the recording medium relating to paper feeding as the paper type, and the speed difference data is calculated for each paper type, and each of the calculated speed differences is calculated. The data is stored in the storage unit in association with each corresponding sheet type, and the correction control unit is input from the belt speed measuring unit with reference to the speed difference data corresponding to the sheet type acquired by the sheet type acquiring unit. It is preferable to correct the detected signal.

  In this case, the timing control of ink ejection is appropriately changed using appropriate speed difference data according to the type of each paper, such as the size, type, or thickness of the recording medium related to the paper supply. Landing deviation can be eliminated.

  In the above invention, the transport path is branched and connected to the normal transport path from the paper feed path through the transport belt to the paper discharge path, and the normal transport path. The recording medium is transferred from the normal transport path and reciprocates the recording medium. The reversing path for reversing the front and back of the paper by returning it to the normal conveying path and the refeeding path from the reversing path to the upstream of the conveying belt are configured in an annular shape, and the refeeding path is divided into a plurality of feeding paths. In the image forming process, the correction control unit includes a speed, sequence, and timing relating to paper feeding for printing on the front surface, paper refeeding through the reversing path, paper reversing, image formation and conveyance. The correction control unit selects and refers to the paper feed route or each speed difference data corresponding to the paper feed route according to the schedule decided by the scheduling unit. Door is preferable.

  In this case, double-sided printing is performed by inserting the paper whose front and back sides are reversed via the reverse path between the papers to be printed on the front side and printing the front side and the back side in parallel. In addition to improving productivity at the time, it is possible to eliminate landing deviation of ink discharge for a recording medium fed through a refeed path.

  As described above, according to the present invention, in the printing apparatus including the conveyance mechanism that conveys the recording medium by the conveyance belt, the difference between the movement speed of the conveyance belt and the movement speed of the recording medium is reflected. It is possible to accurately control ink discharge during printing and prevent landing deviation.

It is a block diagram which shows the outline | summary of the conveyance path | route in the printing apparatus which concerns on 1st Embodiment. It is a functional block diagram which shows the module regarding the discharge timing control which concerns on 1st Embodiment. It is a block diagram which shows the module regarding the discharge timing control of the system control part which concerns on 1st Embodiment, and its peripheral device. It is explanatory drawing which shows the positional relationship of the speed measurement means in the periphery of the conveyance belt which concerns on 1st Embodiment from the side. It is a graph which shows the image shift amount of the recording medium by the speed difference of each point which concerns on 1st Embodiment. It is a graph which shows the speed difference data which concern on 1st Embodiment. It is a block diagram which shows typically the operation | movement of the discharge timing control which concerns on 1st Embodiment. It is a flowchart figure which shows the processing step of the speed difference data generation method which concerns on 1st Embodiment. It is a flowchart figure which shows the process step of the discharge timing control method which concerns on 1st Embodiment. It is explanatory drawing regarding correction | amendment of an encoder signal at the time of controlling the discharge timing of the ink which concerns on 1st Embodiment.

[First Embodiment]
(Overall configuration of printing device)
Embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a diagram illustrating an outline of a conveyance path of the printing apparatus 100 according to the present embodiment. FIG. 1B is a diagram schematically showing the sheet feeding path FR, the normal transport path CR, and the reversing path SR.

  In this embodiment, the printing apparatus 100 includes a plurality of ink heads on which a large number of nozzles are formed, discharges black or color ink from each ink head, performs printing in line units, and prints on a recording medium on a conveyance belt. An ink-jet line color printer that forms a plurality of images so as to overlap each other will be described as an example.

  As shown in FIG. 1A, the printing apparatus 100 is an apparatus that forms an image on the surface of a recording medium that is transported on an annular transport path. This transport path is branched and connected to the normal transport path CR from the paper feed path FR through the transport belt 160 to the paper discharge path DR1 and the normal transport path CR, and the recording medium is transferred from the normal transport path CR to record. The reversing path SR is configured to reverse the front and back of the sheet by reciprocating the medium and returning it to the normal transport path CR.

  In the paper feed path FR, the side paper feed driving unit 220 for feeding paper from the side paper feed tray 120 and the tray 1 for feeding paper from the paper feed trays 130 (130a, 130b, 130c, 130d) are provided. A drive unit 230a, a tray 2 drive unit 230b,... Are provided. Thus, a sheet feeding unit for feeding the recording medium to the registration unit R is configured.

  Furthermore, any of the drive units (tray 1 drive unit 230a, tray 2 drive unit 230b...) In the above-described paper feed path FR includes a drive mechanism composed of a plurality of rollers or the like, and is loaded on a paper feed tray or a paper feed tray. The recorded recording media are taken one by one and conveyed in the direction of the resist portion R. Each drive unit can be driven independently, and necessary drive unit operations are performed in accordance with a paper feed mechanism that feeds paper.

  The normal conveyance path CR is a part of the circulation conveyance path, and is a path from the paper feed path FR for supplying the recording medium to the paper discharge path DR1 through the head unit 110, and recording is performed on the normal conveyance path CR. An image is formed on the upper surface of the medium.

  In the normal conveyance path CR, a registration driving unit 240 that guides the recording medium to the registration unit R, a driving roller 162 that moves the conveyance belt 160 provided on the facing surface of the head unit 110 endlessly, and a conveyance direction side are sequentially arranged. The first upper surface transport driving unit 260 and the second upper surface transport driving unit 265, the upper surface discharge driving unit 270 for guiding the printed recording medium to the paper discharge port 140, and driving means for drawing the recording medium into the reverse path SR for back surface printing are provided. It has been. Each drive unit includes a drive mechanism composed of one or a plurality of rollers or the like, and conveys the recording medium one by one along the conveyance path. Each drive unit can be driven independently, and necessary drive unit operations are performed in accordance with the conveyance status of the recording medium.

  The conveying belt 160 is stretched around a driven roller 161 and a driving roller 162 disposed at the front end and the rear end of the surface facing the head unit 110, and rotates in the clockwise direction in the drawing. Further, on the upper surface of the transport belt 160, ink heads of four colors are arranged side by side along the belt moving direction, and a head unit 110 that forms a color image so as to overlap a plurality of images is opposed to the head unit 110. Yes.

  In the normal conveyance path CR according to the present embodiment, on the upstream side of the conveyance belt 160, the path for supplying the recording medium to the conveyance belt 160 is an upstream path, and on the downstream side of the conveyance belt 160, the conveyance belt 160. A path for sending a recording medium from the recording medium is a downstream path.

  The upstream path is formed such that a plurality of paper feed paths are gathered to reach the registration portion R upstream of the conveyance belt 160, while the plurality of paper discharge paths are branched from the conveyance belt 160 in the downstream path. Yes. A refeed path from the reversal path SR to the registration unit R is included in the sheet feed path FR, and gathers with other sheet feed paths to reach the registration unit R. In the paper feed path FR, as a paper feed mechanism for supplying the recording medium, a side paper feed stand 120 disposed outside the side surface of the housing and a plurality of paper feed trays (130a, 130a provided inside the housing) are provided. 130b, 130c, 130d).

  The recording medium fed from one of the side paper feed tray 120 and the paper feed tray 130 is conveyed along a paper feed path FR in the housing by a driving mechanism such as a roller, and the leading portion of the recording medium. To the resist portion R which is the reference position. A head unit 110 including a plurality of ink heads is provided further on the registration direction R in the transport direction side. The recording medium is image-formed line by line with ink ejected from each ink head while being conveyed at a speed determined by printing conditions by a conveying belt 160 provided on the opposite surface of the head unit 110.

  In the downstream path, a path extending from the conveyance belt 160 located at the lower part of the apparatus to the discharge path DR1 at the upper part of the apparatus, and a straight discharge path extending straight from the conveyance belt 160 in the horizontal direction to the outside of the apparatus side. DR2 is branched. The paper discharge path DR1 is provided with a paper discharge port 140 as a paper discharge mechanism for discharging a printed recording medium, and the straight paper discharge path DR2 is provided with an external paper discharge tray 141.

  The printed recording medium is further conveyed on the normal conveyance path CR by a driving mechanism such as a roller. In the case of single-sided printing in which printing is performed only on one side of the recording medium, the paper is directly discharged to the paper discharge port 140 through the paper discharge path DR1, and is discharged as a tray for the paper discharge port 140. It is loaded on the table 150 with the printing surface facing down. The paper discharge table 150 has a tray shape protruding from the housing, and has a certain thickness. The sheet discharge table 150 is inclined, and the recording medium discharged from the sheet discharge port 140 is naturally arranged and overlapped by a wall formed at a position below the inclination.

  On the other hand, in the case of double-sided printing in which printing is performed on both sides of the recording medium, the front surface (the first printed surface is “front surface” and the next printed surface is “back surface”). Without being guided to the side, it is further transported in the housing and sent out to the reversing path SR. For this reason, the printing apparatus 100 is provided with a switching mechanism 170 for switching the transport path for backside printing, and the recording medium that has not been sent to the discharge path by the switching mechanism 170 is drawn into the reversing path SR.

  The reversal path SR is branched and connected to the normal transport path CR, the recording medium is transferred from the normal transport path CR, and the recording medium is reciprocated (switched back) to return to the normal transport path CR to reverse the front and back of the recording medium. A reversing path and a transport mechanism are provided. The reversing path SR is provided with a reversing drive unit 281 and a refeed driving unit 282 for reversing the recording medium and guiding it to the junction. The reversal path SR can be transported at a speed different from that of the normal transport path CR. When the recording medium is taken over from the normal transport path CR, acceleration / deceleration is performed, or the stop time at the time of switchback is extended. It can be shortened.

  Then, the recording medium reversed by the reversing path SR is returned to the normal conveying path CR from the switching mechanism 172 via the refeeding path by a driving mechanism such as a roller, and the registration unit R is moved from the refeeding path. After that, the paper is fed again, and the back side is printed by the same procedure as that for the front side. Thereafter, the recording medium on which the back side is printed and the images are formed on both sides is led to the paper discharge port 140 through the paper discharge route DR1 and discharged, and the paper discharged as a receiving base of the paper discharge port 140 is discharged. It is loaded on the table 150. In the present embodiment, switchback at the time of duplex printing is performed using a space provided in the paper discharge tray 150.

  In the printing apparatus 100, the recording medium that has been printed on one side is also re-fed to the registration portion R that is the reference position of the leading portion of the fed recording medium. For this reason, a junction point where the conveyance path of the newly fed recording medium and the refeed path where the recording medium for backside printing is circulated is merged is formed immediately before the registration portion R. Is done. The registration unit R sends out the recording medium in the vicinity of the junction between the paper feed path FR and the normal transport path CR.

  Further, in this embodiment, after feeding a certain recording medium, waiting for the recording medium to be printed and discharged, the next recording medium is not fed, but the preceding recording is performed by scheduling. Before the medium is discharged, the subsequent recording medium is fed and can be continuously printed at a predetermined interval. Therefore, in normal scheduling at the time of duplex printing, a space is secured in advance so as to secure a position where the recording medium returned from the reversing path SR is inserted when feeding the recording medium on the front surface. Thereby, in this apparatus, printing on the front surface and printing on the back surface can be performed in parallel, and half the productivity can be ensured with respect to single-sided printing.

(Print control module)
In the present embodiment, as illustrated in FIG. 1A, the printing apparatus 100 includes an arithmetic processing unit 330. The arithmetic processing unit 330 is configured by a processor such as a CPU or DSP (Digital Signal Processor), memory, hardware such as other electronic circuits, software such as a program having the function, or a combination thereof. Various functional modules are virtually constructed by appropriately reading and executing a program, and various functional modules for processing related to image data, operation control of each unit, and user operations are constructed by each constructed functional module. Process. In addition, an operation panel 340 is connected to the arithmetic processing unit 330, and an instruction and a setting operation by a user can be received through the operation panel 340.

  The above-described ejection timing control in the head unit 110 is performed by the print control system module of the arithmetic processing unit 330. FIG. 2 is a functional block diagram showing modules related to printing control of the head unit 110 in the arithmetic processing unit 330, and FIG. 3 is a block diagram showing modules related to printing control in the system control unit 350 according to the present embodiment. . The “module” used in the description refers to a functional unit that is configured by hardware such as an apparatus or a device, software having the function, or a combination thereof, and achieves a predetermined operation. .

  As shown in FIGS. 2 and 3, in the present embodiment, the print control module 335 related to print control in the arithmetic processing unit 330 mainly includes a speed difference data calculation unit 331, a correction control unit 332, and each discharge control unit. 334 and a drive control unit 336, and a storage unit 333, a belt correction data storage unit 337, a speed measurement unit 310, and a system control unit 350 are connected to the print control module 335.

  Then, in the ejection timing control, the print control module 335 determines the image based on the difference between these speeds from the belt moving speed, the paper feeding side speed, and the paper discharging side speed measured by each measuring unit of the speed measuring unit 310. Data corresponding to the positional deviation is calculated as speed difference data and stored in the storage unit 333. Using the speed difference data, the correction control unit 332 uses a plurality of data so that the positional deviation between the plurality of images is reduced. The timing of image formation by the ink head is controlled. As a calculation processing method in the correction control unit 332, it is only necessary to control so that the positional deviation between the plurality of images is reduced as a result, and the calculation is performed so as to eliminate the speed difference directly obtained from the speed difference data. Control may be performed, or calculation control may be performed so as to eliminate the deviation amount obtained based on the speed difference data.

  The speed measuring unit 310 is a module group that detects the belt moving speed of the conveying belt 160 and the moving speed of the recording medium, and includes a driven roller encoder 312, a paper feed side encoder 313, a paper discharge side encoder 314, and a paper feed side. And paper sensors 315 and 316 that detect the leading or trailing edge of the recording medium 10 on the paper discharge side, and a belt HP sensor 311 that detects one circumference of the belt, and obtains input signals from these sensors, The data is transferred to each module in the arithmetic processing unit 330 while being synchronized.

  Specifically, the driven roller encoder 312 is a belt measuring unit that is provided on the driven roller 161 and measures the moving speed of the conveying belt 160 by measuring the angular speed of the driven roller 161 as shown in FIG. The paper feed side encoder 313 is upstream speed measuring means for measuring the moving speed of the recording medium entering the transport belt 160 as the paper feed side speed on the upstream side of the upper surface of the transport belt 160. Is a downstream speed measuring means for measuring the moving speed of the recording medium sent from the conveyor belt 160 as the discharge side speed on the downstream side of the upper surface of the conveyor belt 160. In the present embodiment, the moving speed of the transport belt 160 is measured by the rotational speed of the driven roller 161, but the configuration may be such that the rotational speed of the driving roller 162 is measured.

  The speed difference data calculation unit 331 converts the data corresponding to the positional deviation of the image based on the difference between these speeds from the belt moving speed, the paper feeding side speed, and the paper discharging side speed measured by each measuring unit. It is a module which calculates as. The speed difference data calculation unit 331 is connected to a driven roller encoder 312, a paper feed side encoder 313, and a paper discharge side encoder 314 as speed measuring means. The speed difference data calculation unit 331 is connected to paper sensors 315 and 316 that detect the leading edge or the trailing edge of the recording medium 10.

  Then, the speed difference data calculation unit 331 acquires a detection signal (pulse width) from the driven roller encoder 312 as the moving speed of the transport belt 160, and at the front or rear of the recording medium 10 detected by the paper sensors 315 and 316. The moving speed of the recording medium 10 is calculated using the end as a reference. Then, the data corresponding to the positional deviation of the image based on the difference between these speeds is calculated as the speed difference data from the belt moving speed of the conveyor belt, the paper feeding side speed and the paper discharging side speed, and the calculated speed difference is calculated. Data is stored in the storage unit 333.

  In this embodiment, the correction control unit 332 is a module that refers to the speed difference data based on the belt moving speed and corrects the detection signal input from the driven roller encoder 312. Specifically, the correction control unit 332 includes sheet sensors 315 and 316 that detect the leading edge or the trailing edge of the recording medium 10 together with the moving speed of the conveying belt 160 that is a detection signal detected by the driven roller encoder 312. The detected detection signal and the speed difference data stored in the storage unit 333 are input, and the correction control unit 332 uses the leading or trailing end of the recording medium 10 detected by the paper sensors 315 and 316 as a reference, the driven roller encoder 312. Is corrected, and the corrected detection signal is input to the belt correction control unit 338.

  In particular, in the present embodiment, the correction control unit 332 sets the respective speeds corresponding to the paper feed path FR where the recording medium related to printing is fed and the paper discharge path DR1 where the recording medium related to printing is discharged. The detection signal input from the driven roller encoder 312 is corrected with reference to the difference data. Further, the correction control unit 332 refers to the speed difference data corresponding to the paper type acquired by the paper type acquisition unit 352 and corrects the detection signal input from the driven roller encoder 312. Further, the correction control unit 332 determines the paper feed path or the paper discharge path according to the schedule determined by the scheduling unit 357, selects and references each speed difference data corresponding to these, and inputs from the driven roller encoder 312. The detected signal is corrected.

  In this embodiment, the paper sensors 315 and 316 are arranged on both the paper supply side and the paper discharge side. However, the paper sensors 315 and 316 may be arranged only on either the paper supply side or the paper discharge side. . For example, when the paper sensor 315 is provided only on the paper supply side, the correction control unit 332 conveys the recording medium conveyed by the paper sensor 315 on the paper supply side and the paper size acquired by the paper type acquisition unit 352. 10 calculates and predicts the timing at which 10 reaches the downstream drive unit 241 (feed rollers 241a, b), and corrects the detection signal input from the driven roller encoder 312.

  The belt correction control unit 338 corrects the detection signal of the driven encoder for each ink head by using the belt profile in which the uneven thickness of the belt is recorded and taking into account the change in the moving speed due to the uneven thickness of the transport belt 160. And a module that inputs to the discharge controller 334. Belt profile data is input from the belt correction data storage unit 337 to the belt correction control unit 338, and the belt home position signal detected by the belt HP sensor 311 that detects one mark (reference mark) around the belt. Is entered.

  The belt correction data storage unit 337 is a memory device that stores correction data recording belt thickness unevenness of the transport belt 160. This belt profile data is obtained by calculating the temporal variation of the speed ratio at two arbitrary measurement points on the surface of the transport belt 160 and converting the thickness unevenness of the transport belt into data from the frequency corresponding to the calculated speed ratio.

  The ejection control unit 334 determines the timing of ink ejection by the ink head based on the detection signal corrected by the correction control unit 332 and the belt correction control unit 338 so that the positional deviation between the plurality of images on the conveyance belt is reduced. The head unit 110 forms a plurality of images on the recording medium 10 according to the control by the discharge control unit 334. In this embodiment, the upstream side of the image forming unit is the driven roller 161 and the downstream side of the image forming unit is the driving roller 162, but the arrangement of these supporting rollers may be reversed.

  The drive control unit 336 is a module that controls the operation of the transport driving unit 200 that drives each part of the transport path. The conveyance driving means 200 is a driving means that is arranged on the conveyance path and moves the recording medium 10 on the conveyance path. In particular, in the present embodiment, as shown in FIG. A registration driving unit 240 (registration rollers 240a and 240b), which is a sheet feeding unit that supplies the recording medium 10 to the conveying belt 160 from the upstream sheet feeding path, and the downstream of the conveying belt 160 are disposed. And a downstream drive unit 241 (sending rollers 241a and 241b) for sending the toner to the downstream path. Further, the transport driving unit 200 includes a driving roller 162 that moves the transport belt 160 endlessly.

  The system control unit 350 is a central processing unit that controls the operation of each module in the processing unit 330. In addition to image processing during printing, the system control unit 350 controls the operation of each driving unit in the transport path through the drive control unit 336. To do. In particular, in the present embodiment, the system control unit 350 is a module that calculates the paper type and the ejection timing correction condition for each path in the control of the ink ejection timing. The system control unit 350 also functions as a communication interface for communication with the outside and data transmission / reception with respect to the operation panel 340.

  Here, calculation of the discharge timing correction condition in the present embodiment will be described. Calculation of the ejection timing correction condition is performed by the system control unit 350 by calculating the conditions of each ink ejection timing based on the transport conditions in each path and the paper type.

  As shown in detail in FIG. 3, the system control unit 350 includes a job data reception unit 351, a paper type acquisition unit 352, an operation signal acquisition unit 353, a scheduling unit 357, an image processing unit 356, and correction condition calculation. Unit 355 and a route information storage unit 354.

  The job data receiving unit 351 is a communication interface that receives job data that is a series of print processing units, and is a module that transfers data included in the received job data to the scheduling unit 357 and the image processing unit 356. The communication here includes, for example, short-range communication such as infrared communication as well as LAN such as intranet (intra-company network) and home network based on 10BASE-T, 100BASE-TX, and the like.

  The image processing unit 356 is an arithmetic processing device that performs digital signal processing specialized for image processing, and is a module that performs image data conversion necessary for printing and executes printing. The image processing unit 356 includes an image formation control unit 356a and a color conversion circuit 356b. The color conversion circuit 356b is a circuit that converts an RGB print image into a CMYK print image, and causes the image formation control unit 356a to execute printing based on the print image for each color. The image formation control unit 356a is a module that controls the driving of the ink heads for each color and controls the entire image formation processing, and forms an image at a timing and a printing speed according to the scheduling by the scheduling unit 357.

  The operation signal acquisition unit 353 is a module that acquires the size, type, or thickness of a recording medium related to paper feeding as a paper type, analyzes the received operation signal, and executes processing according to a user operation to other modules. Let In particular, in the present embodiment, the operation signal acquisition unit 353 is configured to perform an instruction operation or a setting operation as to whether or not the user executes the ejection timing process from the operation panel 340 or a printer driver connected through the communication interface 341. Alternatively, paper settings are accepted. Necessity and conditions of the ejection timing control received by the operation signal acquisition unit 353 are input to the correction condition calculation unit 355, and the paper setting is input to the paper type acquisition unit 352.

  The paper type detection mechanism 500 is various sensors that acquire the size, type, or thickness of a recording medium related to paper feeding as the paper type, and is arranged on the transport path, and the presence / absence (passage of the recording medium 10 related to paper feeding) ) Or a sensor that detects the size, type, or thickness of the recording medium 10.

  The paper type acquisition unit 352 is a module that acquires, as paper type data such as the size, type, or thickness of the recording medium 10 related to paper feeding, detected by the paper type detection mechanism 500 or the operation signal acquisition unit 353. Then, the paper type acquisition unit 352 transmits the acquired paper type data to the correction condition calculation unit 355 during the printing process.

  The path information storage unit 354 is a module that stores the transport conditions of each paper feed path FR and each paper discharge path DR1, and transmits the transport conditions according to the selected transport path to the correction condition calculation unit 355 during the printing process. is there. This transport condition includes the length of the paper feed path and the paper discharge path, the number of bends, or the number of rollers, and further stores the acceleration / deceleration of the registration roller in association with each other.

  The scheduling unit 357 is a module that determines the speed, order, and timing related to paper feeding for printing on the front surface, refeeding of paper whose front and back are reversed through an inversion path, and image formation and conveyance in the image forming process. It is. Then, based on the schedule determined by the scheduling unit 357, the image formation control unit 356a and the print control unit 335 execute an image formation process and a conveyance operation.

  The correction condition calculation unit 355 is a module that calculates a correction condition for adjusting the timing of ink ejection in consideration of the conveyance conditions of each path and the paper type. Specifically, the correction condition calculation unit 355 collates the respective conveyance conditions in the plurality of paper feed paths and downstream paths stored in the path information storage unit 354 as conveyance conditions unique to the conveyance path, and obtains a paper type acquisition unit. Based on the paper type acquired by 352, the correction condition for each route is calculated and transmitted to the speed difference data calculation unit 331.

  In addition, the correction condition calculation unit 355 collates the schedule in the scheduling unit 357, collates what recording medium 10 is supplied from which paper feed path, and reads the conveyance condition for each recording medium. The correction condition calculated for each recording medium is notified to the correction control unit 332.

  The storage unit 333 is a memory device that stores the speed difference data calculated by the speed difference data calculation unit 331, and records and holds the speed difference data of the recording medium 10 calculated by the speed difference data calculation unit 331 during printing. , And input to the correction control unit 332 as required. Specifically, as shown in FIGS. 5A to 5D, the speed difference data records the image shift amount of the recording medium due to the speed difference at each point, and each speed (feed-side speed V1). , The belt moving speed V2, and the discharge side speed V3) are patterned for each combination. A detailed description of FIG. 5 will be given later. In the ejection timing correction based on the speed difference data, as shown in FIG. 6A, data obtained by reversing the positive / negative so as to cancel out the image shift amount recorded in the speed difference data is used as the correction data. . In this embodiment, the timing for acquiring the speed difference data of the recording medium does not need to be performed for each printing process. For example, when printing starts, when the environment changes, when the time changes, when maintenance occurs, when the platen moves up and down It can also be triggered by.

  Further, the speed difference data stored in the storage unit 333 includes each speed difference data (predetermined pattern) as shown in FIG. 6B, the paper feeding side speed V1, the belt moving speed V2, and the paper discharging side speed V3. A predetermined pattern can be searched by index data T1 to Tn associated with the magnitude relationship between the belt moving speed V2 and the belt moving speed V2. Specifically, the index data T1 to Tn are created for each paper type. In each index data, the speed is determined from the combination of the paper feed path (FR) and the downstream path (DR) and the speed difference size pattern. The change patterns f111 to f432 are referred to. The paper type here includes paper quality, the size, type, or thickness of the recording medium as parameters, and index data T1 to Tn are associated with each combination of these parameters.

  For example, if the index data T1 is assigned to A4 size plain paper, the paper feed path to which the paper feed tray storing the recording medium is connected is extracted from the paper detection mechanism and job data. The scheduling unit 357 determines at which timing the sheet is discharged from which discharge path, and the system control unit 350 calculates these as correction conditions and inputs them to the correction control unit 332.

  The correction control unit 332 collates the index data T1 referring to the speed difference data based on the correction condition, the speed difference calculated by the speed difference data calculation unit 331, and the magnitude relationship between the speeds V1 to V3. Select the corresponding speed difference data, read it and refer to it. For example, when the A4 size plain paper is fed from the paper feed path (FR2) and discharged from the paper discharge path (DR1), the speed difference data f121 is read when V1 <V2 and V2 <V3. Will be.

  And the operation | movement in discharge timing control of the arithmetic processing part 330 which has such a structure is as follows. FIG. 7 is a block diagram schematically showing the operation during the printing process. Here, it is assumed that the speed difference data is already stored in the storage unit 333.

  First, when the printing process is started, the stored speed difference data is read from the storage memory and input to the correction control unit 332. In addition, print start job data is input to the system control unit 350, and correction conditions related to ink ejection control are input from the system control unit 350 to the correction control unit 332 in accordance with the print mode, paper size, and the like included in the job data. Is done.

  Next, when the printing process is started, the speed difference data calculation unit 331 detects each speed of the driven roller by the leading or trailing end of the recording medium 10 detected by the paper sensors 315 and 316 and the driven roller encoder 312. Then, the moving speed of the conveyor belt 160 is measured (S101).

  Based on the measurement result, the ejection control of the head unit 110 is performed. In this discharge control, the correction control unit 332 performs the corresponding paper feed path, paper discharge path, and paper stored in the storage unit 333 based on the discharge timing correction condition calculated by the system control unit 350 (S106). By referring to the speed difference data of the type (S102), the encoder detection signal input from the driven roller encoder 312 is corrected so that the positional deviation between the plurality of images on the conveyor belt 160 is reduced (S104), and the discharge control is performed. To the unit 334.

  Thereafter, the ejection control unit 334 controls the timing of each image formation by each ink head based on the corrected encoder detection signal (S105), and each ink head controls the ink according to the control by the ejection control unit 334. Are ejected to form a plurality of images on the recording medium.

  In the present embodiment, when calculating the final discharge timing signal, the belt profile in which the unevenness of the belt thickness is recorded is used to take into account the change in the moving speed due to the unevenness of the thickness of the transport belt 160, and the landing deviation Is corrected (S103). This belt profile is correction data obtained by calculating the temporal variation of the speed ratio at two arbitrary measuring points on the surface of the conveyor belt 160 and recording the belt thickness unevenness of the conveyor belt 160 from the frequency corresponding to the calculated speed ratio. is there.

(Speed difference data generation method)
In the present embodiment, the speed difference data described above is generated by the speed difference data calculation unit 331 before the printing process is started, and is installed in the storage unit 333. FIG. 8 is a flowchart showing processing steps of the speed difference data generation method according to the present embodiment.

  The speed difference data is calculated from the belt moving speed, the paper feed side speed, and the paper discharge side speed measured by each measuring means by the speed difference data calculation unit 331, based on the difference between these speeds. Corresponding data is calculated as speed difference data.

  First, a paper feeding operation is started (S401), and the speed difference data calculation unit 331 detects signals from each sensor and encoder (S402). Specifically, as the belt moving speed of the conveying belt, the driving roller 162 that supports the conveying belt 160 is driven, and the angular velocity of the driven roller 161 by the driven roller encoder 312 and the detection signals from the paper sensors 315 and 316 are the speed difference. The data is input to the data calculation unit 331. The speed difference data calculation unit 331 extracts a detection signal from the driven roller encoder 312 and records the recording medium on the conveyance belt 160 with reference to the leading edge or the trailing edge of the recording medium 10 detected by the sheet sensors 315 and 316. 10 movement speeds are calculated (S403).

  On the other hand, on the upstream side and the downstream side of the transport belt 160, the moving speed of the transported recording medium 10 is measured by the paper feed side encoder 313 and the paper discharge side encoder 314 (S404). Entered.

  Then, the speed difference data calculation unit 331 determines each speed based on the belt moving speed detected by the driven roller encoder 312 and the moving speed of the recording medium detected by the paper feed side encoder 313 and the paper discharge side encoder 314. Data corresponding to the positional deviation of the image based on the difference is calculated as speed difference data (S405). Then, the speed difference data is processed by the speed difference data calculation unit 331 to generate speed difference data, and the speed difference data is transmitted to the storage unit 333 and stored (S406). In this storage, the above-described index data is generated and associated with each speed difference data.

  Here, the speed difference data calculation method in step S405 described above will be described. As shown in FIG. 4, a paper feed side encoder 313 is disposed on the upstream side of the transport belt 160, and a paper discharge side encoder 314 is disposed on the downstream side of the transport belt 160. Ink heads are arranged. The driven roller 161 is provided with a driven roller encoder 132. Then, the speed at which the recording medium moves on the conveyance belt 160 is set to be one pulse of each encoder, and data corresponding to the image positional deviation based on the difference between the speeds is calculated as speed difference data.

  Specifically, as a method of calculating the speed difference between the moving speeds, the belt moving speed of the conveying belt 160 is set to V2, the moving speed of the recording medium 10 at a point upstream of the conveying belt 160 is set to the sheet feeding side speed V1, and the conveying belt is used. 160, if the moving speed of the recording medium 10 at a downstream point is the discharge-side speed V3, the speed difference of V1 with respect to V2 is Dk = (V1-V2) / V2, and the speed difference of V3 with respect to V2 is Dh = ( V3-V2) / V2. The speed difference data D based on the difference in moving speed of the recording medium 10 is D = Dk + Dh.

  First, a case where the recording medium 10 enters the conveyance belt 160 will be described. As shown in FIG. 4, the recording medium 10 is sandwiched between registration rollers 240 a and 240 b on the upstream side of the conveyance belt and enters the conveyance belt 160. Therefore, the sheet feeding side speed V1 of the recording medium 10 entering the conveyance belt is the moving speed of the upstream registration rollers 240a and 240b.

  If the sheet feeding speed V1 of the recording medium 10 upstream of the conveying belt is slower than the belt moving speed V2, the recording moves on the conveying belt until the nipping by the registration rollers 240a and b is eliminated. The moving speed of the medium 10 is also V1, and the medium 10 is conveyed to the position of the ink head with a delay from the ink discharge timing. As a result, an image shift occurs in the front end direction of the recording medium 10, and the amount of image shift greatly shifts from the front end side of the recording medium to the downstream side of the conveyance belt 160.

  Next, a case where the recording medium 10 is sent out from the conveyance belt 160 to the paper discharge side will be described. As shown in FIG. 4, the recording medium 10 is sandwiched between delivery rollers 241a and 241b on the downstream side of the conveyance belt, and sent out to the paper discharge path. Accordingly, the discharge side speed V3 of the recording medium 10 sent out from the conveying belt is the moving speed by the downstream sending rollers 241a and 241b.

  Therefore, when the discharge side speed V3 of the recording medium 10 on the downstream side of the conveying belt is higher than the belt moving speed V2, when the recording medium 10 is nipped and conveyed by the delivery rollers 241a and 241b, The moving speed of the recording medium 10 that moves is V3, and passes the position of the ink head earlier than the ink ejection timing. As a result, an image shift occurs on the rear end side of the recording medium 10, and the amount of image shift increases from the rear end side of the recording medium to the upstream side of the conveying belt 160.

  FIG. 5 is a graph showing the image shift amount of the recording medium due to the speed difference at each point according to the present embodiment. In FIG. 5, the vertical axis indicates the amount of image shift, the plus side indicates that it is shifted toward the leading end side of the recording medium, and the minus side indicates that it is shifted toward the trailing end side of the recording medium. Yes. The horizontal axis indicates the position of the recording medium, and the plus direction indicates the rear end of the recording medium.

  When the speed difference at each point of the conveyor belt 160 is V1 <V2 and V2 <V3, as shown in FIG. 5A, an image shift occurs at the leading edge and the trailing edge of the recording medium. When V1 <V2 and V2> = V3, as shown in FIG. 5B, an image shift occurs only at the leading edge of the recording medium. When V1> = V2 and V2 <V3, as shown in FIG. 5C, an image shift occurs only at the rear end of the recording medium. When V1> = V2 and V2> = V3, as shown in FIG. 5D, no image shift occurs on the recording medium 10.

  More specifically, such an image positional shift based on the speed difference between the speeds V1 to V3 occurs in accordance with a relative change in the degree of influence acting on the recording medium due to the speed difference. The relative change in the degree of influence due to this speed difference includes the relative change in the contact area between each belt and the recording medium, and the frictional force (dynamic friction, static friction, etc.) between each belt and the recording medium as the contact area changes. Changes. For example, when the recording medium is moved from the paper feed side to the transport belt 160, the transport speed from the paper feed side is slow and the transport speed by the transport belt 160 on the downstream side is fast. As the belt 160 changes, the contact area with respect to both belts changes relatively, and in accordance with the change in the contact area and the change in the friction force of the recording medium with respect to each belt, the recording medium moves backward in the moving direction. As a result, tension occurs, the recording medium moves relative to the belt, and an image position shift occurs based on the speed difference between the belts. The speed difference data is data in which the positional deviation of these images is recorded.

  As described above, the speed difference data calculation unit 331 corresponds to the image positional deviation based on the difference between these speeds from the belt moving speed, the paper feeding side speed, and the paper discharging side speed measured by each measuring unit. Data is calculated as speed difference data. A system control unit 350 is connected to the speed difference data calculation unit 331, and the speed difference is calculated according to correction conditions for each of a plurality of paper feed paths, a plurality of paper discharge paths, and paper types input from the system control unit 350. Each data is calculated.

  Specifically, the conveyance means on the paper feed side that causes the recording medium 10 to enter the conveyance belt varies its moving speed in correspondence with the conveyance means from the plurality of paper feed paths (FR1 to FR3) located upstream thereof. I am letting. Then, the speed difference data calculation unit 331 calculates speed difference data for each of the plurality of paper feed paths (FR1 to FR3). In addition, the discharge-side conveying means for sending the recording medium 10 from the conveyance belt varies its moving speed in correspondence with the conveying means from a plurality of downstream discharge paths. Then, the speed difference data calculation unit 331 calculates speed difference data for each paper discharge path. Furthermore, since various paper sizes can be transported on the transport path, the speed difference data calculation unit 331 calculates speed difference data for each paper type of the recording medium 10. Then, the speed difference data calculation unit 331 calculates speed difference data for each paper type.

(Print control method)
By operating the print control module having the above configuration, the print control method including the ejection timing control can be implemented. FIG. 9 is a flowchart showing processing steps of the print control method according to the present embodiment.

  First, when print processing is started, when job data is input to the system control unit 350, it is stored according to the print conditions (print mode, paper size, paper type, etc.) included in the job data. The selected speed difference data is selected and read out and transferred to the correction control unit 332 (S201).

  Next, the paper feeding operation is started and the printing process is actually started (S202). When the printing process is started, the arithmetic processing unit 330 acquires a signal from each encoder. Specifically, detection signals from the driven roller encoder 312 and detection signals from the paper sensors 315 and 316 are input to the speed difference data calculation unit 331 (S203). Thus, the moving speed of the recording medium 10 on the conveyor belt 160 is measured (S204).

  Then, the correction control unit 332 corrects the detection signal of the driven roller encoder 312 (S205). When correcting the detection signal of the driven roller encoder 312, the correction control unit 332 refers to the speed difference data stored in the storage unit 333. In the speed difference data, an image shift amount from the front end to the rear end of the sheet is recorded for each speed difference between the upstream side and the downstream side of the conveyance belt 160. The correction control unit 332 stores the speed difference data in FIG. As shown in FIG. 5, the detection signal from the driven roller encoder 312 is corrected based on the speed difference data so as to cancel out the deviation amount recorded in the speed difference data.

  The detection signal corrected by the correction control unit 332 is input to each ejection control unit 334. In this correction, the value of the speed difference data is read in accordance with the rotation period of the conveyor belt 160 based on the home position signal, and the encoder detection signal input from the driven roller encoder 312 as shown in FIG. Depending on the correction value, it is advanced or delayed so that the positional deviation between the plurality of images is adjusted and input to the ejection control unit 334.

  The ejection control unit 334 controls the timing of image formation by each head unit 110 based on the corrected encoder detection signal (S206), and each ink head supplies ink according to the control by the ejection control unit 334. A plurality of images are formed on the recording medium by discharging.

(Action / Effect)
According to such an embodiment, the belt moving speed that is the moving speed of the conveying belt 160, the paper feeding side speed that is the moving speed of the recording medium upstream and downstream of the conveying belt, and the paper discharging side speed are measured. The data corresponding to the positional deviation of the image based on the difference in each speed is used as the speed difference data. In other words, in the present embodiment, data corresponding to the positional deviation of the image based on the difference between the moving speed of the conveying belt and the moving speed of the recording medium is calculated as speed difference data and stored in the storage unit 333. deep. In the actual printing process, the belt moving speed is measured, and the speed difference data is reflected in the measurement result so that the printing position is not shifted due to the speed difference between the conveying belt speed and the moving speed of the recording medium. The timing can be changed to eliminate landing deviation.

  Further, in the present embodiment, the speed difference data is calculated for each corresponding paper feed path, and the speed difference data corresponding to the paper feed path to which the recording medium 10 is fed is referred to during printing. In a paper feed path FR configured by a collection of a plurality of paper feed paths FR and re-feed paths, the ink ejection timing control operation is changed according to the conveyance conditions specific to each path, so that landing deviation is more appropriately performed. Can be eliminated.

  On the other hand, in the present embodiment, on the downstream side of the transport belt 160, a plurality of paper discharge paths DR1 are branched from the normal transport path CR, and the speed difference data is circulated on the normal transport path CR side and the paper discharge path DR1. The calculated speed difference data is stored in the storage unit 333 in association with each corresponding paper discharge path. As a result, the correction control unit 332 can correct the detection signal input from the driven roller encoder 312 with reference to the speed difference data corresponding to the paper discharge path through which the recording medium is sent, and is specific to each path. The operation of the ink ejection timing control is changed according to the transport conditions, and landing deviation can be more appropriately eliminated.

  In the present embodiment, the speed difference data is calculated for each paper type, such as the size, type, or thickness of the recording medium related to paper feeding, and stored in the storage unit 333 in association with each corresponding paper type. The correction control unit 332 refers to the speed difference data corresponding to the paper type acquired by the paper type acquisition unit 352. As a result, in the present embodiment, the operation of the ink ejection timing control can be appropriately changed according to the type of each paper such as the size, type, or thickness of the recording medium related to paper feeding, and the landing deviation can be more appropriately performed. Can be eliminated.

  In the present embodiment, the correction control unit 332 is connected to a scheduling unit 357 that performs scheduling including switchback processing, and the correction control unit 332 follows the schedule determined by the scheduling unit 357. Each speed difference data corresponding to the paper path can be selected and referred to. For this reason, in the present embodiment, a sheet whose front and back sides are reversed via the reversing path SR is inserted between the sheets for printing on the front side, and scheduling is performed so that printing on the front side and printing on the back side are performed in parallel. As a result, productivity at the time of duplex printing can be improved, and landing deviation of ink discharge acting on the recording medium in the refeed path can be eliminated.

[Second Embodiment]
In the first embodiment described above, the image misalignment is adjusted by controlling the ink discharge timing. However, in the second embodiment, in addition to the ink discharge timing control in the discharge control unit, the drive for transporting the recording medium 10 is performed. You may make it control the drive speed of a means collectively.

  For example, in the discharge timing control and the paper transport control, the print control module performs image processing based on the difference between these speeds from the belt moving speed, the paper feed side speed, and the paper discharge side speed measured by each speed measurement unit 310. Data corresponding to the misregistration is calculated as speed difference data, and the correction control unit 332 controls the timing of image formation by the plurality of ink heads so that the misregistration between the plurality of images is reduced, and also performs drive control. The unit 336 controls the moving speed of the recording medium 10 by the transport driving unit 200 disposed on the upstream side and the downstream side of the transport belt 160 in synchronization with the ink ejection timing corrected by the correction control unit 332.

  Specifically, as shown in FIG. 9, the correction control unit 332 corrects the detection signal from the driven roller encoder 312 based on the speed difference data (S205). In the present embodiment, the detection signal corrected by the correction control unit 332 is input to each ejection control unit 334 and drive control unit 336 in the next step S206. The ejection control unit 334 controls the timing of image formation by each head unit 110 based on the corrected encoder detection signal, and the drive control unit 336 controls each timing based on the corrected encoder detection signal. Paper conveyance by the conveyance driving unit 200 is controlled. The transport driving unit 200 transports the recording medium 10 to the transport belt 160 according to the control by the drive control unit 336, and each ink head ejects ink according to the control by the ejection control unit 334, and a plurality of inks are printed on the recording medium. The image is formed.

(Action / Effect)
According to such an embodiment, the belt moving speed that is the moving speed of the conveying belt 160, the paper feeding side speed that is the moving speed of the recording medium upstream and downstream of the conveying belt, and the paper discharging side speed are measured, Data corresponding to the positional deviation of the image based on these speed differences is used as speed difference data. In the actual printing process, the speed difference data is reflected in the control of the belt moving speed and the control of the ink discharge so that the printing position shift due to the speed difference between the conveying belt speed and the moving speed of the recording medium does not occur. Then, the moving speed of the recording medium 10 by the transport driving means 200 is changed. As a result, according to the present embodiment, landing deviation can be more reliably resolved by changing the printing timing.

CR: Normal transport path DR1: Paper discharge path DR2: Straight paper discharge path FR ... Paper feed path R ... Registration section SR ... Reverse path 10 ... Recording medium 100 ... Printing device 110 ... Head unit 120 ... Side paper feed stand 130 ... Feed Paper tray 132 ... driven roller encoder 140 ... paper discharge port 141 ... external paper discharge tray 150 ... paper discharge table 160 ... transport belt 161 ... driven roller 162 ... drive roller 170, 172 ... switching mechanism 200 ... transport drive means 220 ... side feed Paper drive unit 230a, 230b ... Tray drive unit 240 (240a, b) ... Registration drive unit (registration roller)
241 (241a, b): downstream drive unit (sending roller)
260: First upper surface transport driving unit 265 ... Second upper surface transport driving unit 270 ... Upper surface discharge driving unit 281 ... Reverse driving unit 282 ... Refeeding driving unit 310 ... Speed measuring unit 311 ... Belt HP sensor 312 ... Driven roller encoder 313 ... Paper feed side encoder 314 ... Discharge side encoders 315, 316 ... Paper sensor 330 ... Calculation processing unit 340 ... Operation panel 331 ... Speed difference data calculation part 332 ... Correction control part 333 ... Storage part 334 ... Discharge control part 335 ... Printing Control module 336 ... drive control unit 337 ... belt correction data storage unit 338 ... belt correction control unit 340 ... operation panel 341 ... communication interface 350 ... system control unit 351 ... job data reception unit 352 ... paper type acquisition unit 353 ... operation signal acquisition Unit 354 ... Path information storage unit 355 ... Correction condition calculation unit 356: Image processing unit 356a ... Image formation control unit 356b ... Color conversion circuit 357 ... Scheduling unit 500 ... Paper type detection mechanism

Claims (7)

An ejection control mechanism of a printing apparatus for ejecting ink from the ink head to form an image on the surface of a recording medium conveyed on a conveyance belt in a conveyance path;
A belt moving speed that is a moving speed of the conveying belt, a sheet feeding side speed that is a moving speed of the recording medium entering the conveying belt upstream of the conveying belt, and a conveying belt that is sent downstream from the conveying belt. A speed difference data calculation unit that calculates data corresponding to the positional deviation of the image based on a difference between the respective speeds of the paper discharge side speed, which is the moving speed of the recording medium, as speed difference data;
In the printing process, based on the speed difference data calculated by the speed difference data calculation unit, the timing of ink ejection by the ink head is controlled so that the positional deviation between the plurality of images on the transport belt is reduced. A discharge control mechanism for a printing apparatus, comprising: a discharge control unit. A storage unit for storing the speed difference data calculated by the speed difference data calculation unit;
A correction control unit that corrects a detection signal input from the belt speed measuring unit with reference to the speed difference data stored in the storage unit based on the belt moving speed in the printing process;
In the storage unit, the speed difference data is stored in association with a magnitude relationship between the paper feeding side speed and the belt moving speed, and the paper discharging side speed and the belt moving speed,
The discharge control mechanism of the printing apparatus according to claim 1, wherein the correction control unit refers to the speed difference data based on the magnitude relationship. The transport path includes an upstream path for supplying the recording medium to the transport belt on the upstream side of the transport belt,
The upstream path is formed such that a plurality of paper feed paths are gathered to reach the upstream side of the conveyor belt,
The speed difference data is calculated for each of the plurality of paper feed paths,
Each calculated speed difference data is stored in the storage unit in association with each corresponding paper feed path,
The correction control unit corrects a detection signal input from the belt speed measuring unit with reference to speed difference data corresponding to a paper feed path through which a recording medium for printing is fed. Item 2. A discharge control mechanism of a printing apparatus according to Item 1. The transport path includes a downstream path for sending the recording medium from the transport belt on the downstream side of the transport belt,
In the downstream path, a plurality of paper discharge paths are branched from the conveyor belt,
The speed difference data is calculated for each of the plurality of paper discharge paths,
Each calculated speed difference data is stored in the storage unit in association with each corresponding paper discharge path,
The correction control unit corrects a detection signal input from the belt speed measuring unit with reference to speed difference data corresponding to a paper discharge path from which a recording medium for printing is discharged. Item 2. A discharge control mechanism of a printing apparatus according to Item 1. Paper type acquisition means for acquiring the size, type or thickness of the recording medium related to paper supply as the paper type;
The speed difference data is calculated for each paper type, and each calculated speed difference data is stored in the storage unit in association with each corresponding paper type,
The correction control unit corrects a detection signal input from the belt speed measuring unit with reference to speed difference data corresponding to the paper type acquired by the paper type acquiring unit. A discharge control mechanism of the printing apparatus described. The transport path is
A normal transport path from the paper feed path through the transport belt to the paper discharge path;
A reversing path that is branched and connected to the normal conveying path, the recording medium is delivered from the normal conveying path, and the recording medium is reciprocated and returned to the normal conveying path to reverse the front and back of the paper;
A refeed path from the reverse path to the upstream side of the conveyor belt;
And is configured in a ring
The refeed path is included in the plurality of feed paths,
In the image forming process, the correction control unit sets the speed, sequence, and timing relating to paper feeding for printing on the front surface, refeeding of paper whose front and back are reversed through the reversing path, and image formation and conveyance. The scheduling part to decide is connected,
The printing according to claim 3, wherein the correction control unit selects and refers to the paper feed path or each speed difference data corresponding to the paper feed path according to the schedule determined by the scheduling unit. Discharge control mechanism of the device. An ejection control method for a printing apparatus that forms an image on a recording medium conveyed on a conveyance path by an image forming unit,
A belt moving speed that is a moving speed of the conveying belt, a sheet feeding side speed that is a moving speed of the recording medium entering the conveying belt upstream of the conveying belt, and a conveying belt that is sent downstream from the conveying belt. A speed difference data calculating step for calculating, as speed difference data, data corresponding to a positional deviation of the image based on a difference between the respective speeds of the paper discharge side speed as the moving speed of the recording medium;
In the printing process, based on the speed difference data calculated by the speed difference data calculation unit, the timing of ink ejection by the ink head is controlled so that the positional deviation between the plurality of images on the transport belt is reduced. A discharge control method for a printing apparatus, comprising: a discharge control step.